Hydraulic drill feed and stroke timing mechanism



SPt- 16, 1952 F. w. KRIEWALL 2,610,528

HYDRAULIC DRILL FEED AND STROKE TIMING MECHANISM Original Filed Nov. 6, 1944 5 Sheets-Sheet 1 .ma /f Sept 16, 1952 F. w. KRlEwALl. 2,610,528

K HYDRAULIC DRILL FEED AND STROKE TIMING MECHANISM Original Filed Nov. 6, 1944 5 Sheets-Sheet 3 Sept. 16, 1952 F w, KRlEwALL 2,610,528

i HYDRAULIC DRILL FEED AND STROKE TIMING MECHANISM .Original Filed NOV. 6, 1944 5 Sheets-Sheet 4 Sept. 16, 1952 F. w. KRlEwALl. 2,610,528

HYDRAULIC DRILL FEED AND STROKE TIMING MECHANISM Original Filed Nov. 6, 1944 5 Sheets-Sheet 5 Affarmey Patented Sept. 16, 1952 y 2,610,52s n I HYDRAULIC DRILL FEED AND s 'rRoKxif4 lTIMING. MECHANISMl Fred W;4 Kriewall, van Dyke, Mich., assignor to;

Leland-Gifford Company, Worcester, Mass., a "j,"

corporation of `Massachusetts I fotminiiat'igii of, application serialI No. 552,212;`

November, 1944. This application November i `22,119.13,'serial No.ciAzsL Y This invention relates vto new anduseiul improvements yin tool feeding andrtool stroke timing mechanisms in machine tools.` I1 he invention is particularly adapted to use on machines inrthe nature of drillingl machines where it Yis desired to drill in short quick steps, as indeep hole and smallholedrilling andvin particularly hard materials; Until the *present invention, holeswere drilled'either in uniform steps orl in steps dependent on the'torque applied to the drill, but this invention provides for adjustable steps of almost any lengtlnor ineiectQshortness de-i sired, by completelyl hydraulic means."

It is another object of the invention'to provide a mechanismv off/this type in whichthe feeding and withdrawal is all 'hydraulically operated and easily adjusted so that a 'positivei feed of the most exible type is provided. 'f i V y It is anotherobjectloffthe'invention to provide a mechanism'ofthis class which will be simplein structure, economical to manufacture, durable.' compact, possessed ofa minimum number of parts and highly elicientinuse(V Y Another object ofthe invention resides in the provision of a hydraulic device for controlling the stroke of a tool such as a drill, to effect extremely short drill feed steps, as for instance, in small and deep hole drilling, and resulting in control of the timing of the cycle of feed, so that this invention in reality relates to timing control of a nature to provide for shorter steps than have been heretofore possible, and consequent pro-- longation of drill life and higher eiciency in general of the machine; and the provision ofa device as above stated which'acts automatically `varying'hardness due to unevenness ini' heat treatment, for example; sothat harder pieces will occasion shorter steps, whereby the machine will always operate at maximum eiiicency and; at best cycling for prolonging the life of -tlie drills.' f A further object of the invention resides in 'the' 8 Claims.- (C1, 77;.32A) N construction 'ai'id'foperation of 'the device for accomplishingv the tool stroke control above referred to, 'byf predetermined but v'adjustable volumes of hydraulic fluid received thereby from tlfiemainY tool; feedA cylinder, and in combination therewithatooloverload reversing device for undue l'resistanoes'sometimes met bythe tool.

` Otlriervobjec'ts will appear hereinafter.

It isA recognized that various changes and modifications Vmaybe made inthe detail of structure illustrated without departing from the invention itself and itv is intended that such changes and variations shall be encompassed within tl'ie''sco'pe ofthe claimswhich-form a part of this specication.- 1- j I Forming apart of this specification are drawings'winwhich:V l f Fig. 1 is a side elevational view of adrill press showing the invention appliedy' f Y -Fig.y i2 is a-frag'menta'ry Vview vof the -power cylinder showing partsin fsection and showing other parts in elevation Vattached thereto.

Fig. 3 is arfragmentaryysectional view, taken on line 3 3 of Fig. 1, l Y

Fig. 4 is a sectional view, taken on line 4 4 ofFig.3, HVV f1 f Fig. 5 is a sectionalview,taken on line' 5 5 0fFg 1 Fig. 6 is a sectional view, taken on substantially line 6 6 of Fg,` Y Y v Fig. 'I is 'a sectional view,ftaken offj g 1? I .c

Fig. 8 is a vertical sectional view through the timing valve, y v Fig. 9 Ais a sectional view, ltaken on line 9 9 ofFig.1',` v f Fig.v 10 is a schematic viewof piping used in the-mechanismf W Y h{Fig} 11 -is` -a fragmentary enlarged plan view on line 1 1 of the tripping'mechanism used inthe invention` with partsbroken awayand parts shown in vsec- Fig. 41.). is a Cf Fig. 11, ij,

-' 'Fig'. 13 is"E a"bottomplarrviewflookingin the direction-offarrow in 'Fig'. l1, i f

sectional view, taken on line |2A-vl2 associated parts." Fig. r`15 is a sectional-view, taken on line 'I 5 l5 of Fig. 14. i

Fig. 29. Y

be floatingly held relative to the slide bar 64,

Fig. 16 is a bottom view of the parts of Fig. 14,

Fig. 17 is a sectional View, taken on line l'I--H of Fig. 16,

Fig. 18 is a perspective View of a tripping mechanism used in the invention,

Fig 19 is a sectional View, taken on line ig-lii of Fig. 412,

Fig. 20 is a sectional view, taken on line 226-26 of Fig. 18,

Fig. 2l is a sectional view, taken of Fig. 14,

Fig. 22'is a fragmentary detailed View of a cam on line 2 i--ZI shown in tripped position for resetting the ma-v chine into original starting position,

the present invention, and f Fig. 29 is a cross-sectional view,'tal ien on line f 29--29 of Fig. 12.

The hydraulic tool involving the present ini vention comprises a drillingv machine having drill 29, Fig. 1, which is adapted to drill a hole in the work 23. The drill is carried by a,r chuck 3S fixed to a shaft 32 journalled-in a bearing block 34 carried by a slide 35 that is slidable axially of the drill shaft 32 on a guideway 39 that is apart of the general frame 4B of the unit, the unit being adapted for support on some convenient base. A motor 42 is carried by the frame i6-and serves to drive, through suitableV gearing, the drill shaft 32, the drive connection between the motor and the drill Vshaft 32 being suchVK that the drill shaft 32 may be moved axially of the motor 4,2 while rotated thereby, this form of drive connection forming no part of the present invention and being well known. YrIhe slide I361s reciprocated hydraulically by a piston 52 disposed `in a cylinder `54 formedl integrally with the general frame 4E atonerside of the spindle and its driving shaft. The piston52 has a piston rod 56 which has internally screw-threaded engagement with a coaxially disposed screwthreaded rod 58 connected with the `slide 36Y so that the piston and slide Yarehcaused to reciprocate as a unit. The piston rod 55 and screw-threaded rod 58 are held locked in any adjusted position by a lock nut 60. The piston is reciprocated Aby the admission of pressure liquid alternatelyk on opposite sides thereof, and the movements of the piston are controlled by a cam slide 62, see Figs. 1, 2, ll, 12, 13, 14, and-21. Said slide includes a generally flat longitudinally extended slide bar 64 that is slidable in a horizontal groove V6610i the frame 40 behind a plate 68,` which is secured to the frame 40 and overlies the upper portion of the front face of the bar and retains the bar in the groove. A bracket 10, see especially Fig. 16, is secured to the forward edgeI of said` bar 64 and has a boss 12- which encircles the piston rod 56 behind the lock nut 6D 'so that the slide bar 64 andthe pistonv reciprocate together.; Said bar 64 has a longitudinal groove 'i4 in itsouter face in which plate 83 of a cam block or control member16, see especially Figs. 6, 12, 1`3an d 19, is slidably retained. The-control member or camy block 'I6 is frictionally held by shoes 230 floating in the grooves or: slide '14... The shoes 230 are disposed in opposite side ywalls of the portion 88 of the cam blockv 1'6 and aremoved against and held to the sides oftheslide by springs2-3I, see This arrangement permits the cam to that is, the cam block is held stationary -asnthe bar 64 moves. Said cam block has an= inclined.

f said` bar.

cam face 18 which leads to a flat or dwell face for giving a slow speed advance of the piston and connected tool. The cam block I6 is movable downwardly along the slide bar 64 a predetermined distance or, more accurately, the slide bar 64 moves, while the cam block 16 is held stationary, during each successive advance of the slide bar and the tool in a manner hereinafter to be explained for the purpose of eiecting a following further advanceof v,the tool each time itis reciprocate'd, until a predetermined advanced position of the tool has been reached. rfhe slide bar 64 has a forwardly extended bar 82 secured to it at its ends by screws 84 and having a groove 88 which confronts the groove 'I4 in said slide Lbar and in which groove 8B the vertical plate 88 of said cam block 1S is movable. The outer 9S, see especially Figs; 11 and 14, is secured in any suitable longitudinally disposed location on Said Vstop cooperates with said cam blockf'l 'in a manner presently to be described. Al cam block 98, see Figs. 11, 14, 12, 18, 15 and 16, is secured adjustably on said bar 82 at or near the end thereof and has means adapted to effect the advancing movement of the piston and tool after it has :been retracted from some intermediately advanced position and also to holdl the piston and tool in a completely retracted position after it has been retracted from a fully advanced position or hask been retracted by manual or other external control during an intermediate part of the` cycle.` Said cam block 88 is provided with a plate'l which underlies the barf82, and said plate has a rearwardly directed inclinedl cam face ;wise or downward direction when viewedas shownin Fig-18 in a depressed position-,hva spring |09, see Fig. 20. Said lever Hifi servesto effect the advance of the piston after it has `been retracted from some intermediately advanced positgi'on.,V Y I 1 Themovernents of the piston are controlled .by hydraulic valves which, in addition to manual operation by which th'e advance of the pistonl can bestarted and the piston can be returned -to fully retracted position at any time under control `of an operative, are operated. automatically 'byv the aforesaid cams 18 |02, and the lever HIS to: effect the desired 'control Yof the mechanism.l Thee valves and the hydraulic system associated with the present apparatus are diagrammatically illustratedin Fig. 10v and will now be described. The hydraulic system includes a continuously operating4 oil pump l l0 preferably, although not necessarily, of the gear type which receives oil flou/from .a reservoirv H52 and forces it'through a ppe l I4 into the cylinder of a compressed air accumula-tori I6 from which the oil flows through` agpipe;` i lli-into avalve housing `|28 having, the piston; valves |22' and |24; therein connectedtogethierfby a valve stem ,126.- The opposite ends of the valve cylinder are yconnectedV by pipes' `|28l and 13,0to pipe 132 whichconducts Yexhaust civ-l back intothe reservoir H72;- A pipe 134` is in. communication with an. intermediate part lof -the valve cylinder and also with-a piston-speed'` controlling valve cylinder. |36 that hasthe'piston y -valve |38 therein which .is .acted .upon byA a spring |46 .to urge the valveV constantly toward theleft. A pipe-.|42 communicates .with an intermediate partof the valve cylinder. |36 and also with the rearor right-hand end of the piston cylinder 54.' kApipe |44 communicates with the forward or left-hand end iof thecylinder 54 and with .a port" |46 in thevalve cylinder |20.. In Fig. 10 the parts are set for a fast forward feed ofthe pistonand tool, the valvesy |122, |24, and also the piston-speed control/valve, beingat the extreme left. The high pressure oil from the pipe ||8 passes'-unthrottledthrough thevalve cylinder |20 and |36 into the rear end of the cylinder 54--behind the piston 52 and therebyadvances the piston at maximum speed, vthe oilfin front of the piston escaping-through the pipe` |44 into the right-hand en d of -the Avalve' cylinder|20 -and through the pipe |30'back into the reservoir I I2. The piston 52 'is also adapte'd'to havea'slower rate of advance in` which case'the piston valves v|22 and |24v are moved' suiciently to the lright tov-'close the exhaust `port |46 and. alsopartially to close the outlet port cornmunicatingwith` the piper |34. `The oil escaping'f-rom the' forward end ofthe piston is now constrained-to pass into the exhaust end of the valve cylinder |20 through a pipe |48 which communicates with theV pipe4 |44 through athrottle valve |50, which throttle valve retards the flow of oil andthereby sets up aback pressure oil on the piston 52 and holds the pis"- tonagainst jumping due to variable resistance betweenthe work andthe tool operated by the piston.A

" The valves |22 and |24 can be advanced toward the right tocompletely close the outlet connected with the pipe |34 and Yalso the lexhaust-port |46 and the outlet ofthe pipe |48`, thereby preventing lflow of oil into and out of bothsides of the piston and holding the-piston 52 immovably in any position in which itfmay have been moved.

movement of the valves |22 and |24 further towardthe right places vthe pipe |34 in communication with the exhaust pipe |28-'and the-pre'ssure Ypipe ||8 in communication with the pipe |44, thereby supplying Ahighpressure oil to the forward end of the piston cylinder54 and' establishingl an unrestricted exhaust passage for the rear end of the cylinder so that the piston 52 is retracted at a rapid rate. The valve cylinders |20 vand |36 .are secured. one against the other to the inner face of a valvesuppo'rting plate |54, which isbolted over a recess |2 in the frame 40 of the' mechanism, 4see Figs. 3 and 21, which recess comprises the oilreservoir ofthe system. The valves |22 and |24 are operated Ibya valve operating member comprising` alshaft |58 which has an arm |60 :fixed` to its upper end, the arm having an upstanding cam pin |62 that is disposedin position to be engaged by the cam blocks .16S and' 98, said arm overlying the top of the valve supporting plate |54 and being disposed in front of the slide 64. A rearwardly extended arm |64 is xed 'to the lower end of the said shaft |58 and;has its endterminated between longitudif nally adjustablescrews |66 carried by ai slide |68 locatedin a groove in the valve cylinder-|20 and having anjarm |510 that `is Aconnected. ;to.` the stem' |26-of said-valve so thatsaidfslide vand valve-f stem are caused .to move-together: 4The .positionofsaid arm |80Y thus` determines the op. eratire condtiomofdhe rristongZ.-` Vilhen the arm|60 is infthejposition illustrated infFi-ge v1.()

with. .itsv :pin 6 2 2 disposed .in .front cfu-buty :out

of engagement with the vcam block 16, the valves are v.in .condition for a rapid advance of the pistonv 52'.. When the, pin |62 is on the dwell portion 80 ofV the caxnjblock. 16,'the setting'ofthe valves -issuchas to giveia slow;or WorkingY ad.- Vance of` the piston. This .is indicated bythe rst dottedline positioned'in Fig. 10. When the pin |62 is in the next advanced position, away from the dwellA portion 80 and, engaged :by the cam face |02 of the. block 98, the valves are in neutral position and the piston 52 is stationary. This is indicated by the second dotted line posi--V tion in: Fig. 10. When the pin |62. isin :the fourth .position .illustrated by the third :dotted line position in Fig. 10, the. mechanism islset for afast return of the piston 52. The arm' L60 is held either in high or slow speed advance .positions or in reverse position by means including la spring-pressed plunger |12 that-hasa-trian gular cam .projection |14 .that abuts vagainsteI similar. vcam projection |16 fixed to 1 the .shaft |58, see Fig. 7. The arrangement of saidcam projections is such that their apexes. coincide somewhere between neutral and slow .speed .positionszofthearm |60 so that when the camprojectionsare in theposition illustratedv in Fig.'10, the-arm |60. is biased toward a high speed position and-when the cam projection |16 is on the other side of. the cam projection'f|.|4,-the ar1`n|60 is biased. toward reverse. The. arm |60 must'v be heldin neutral positionl against the `action of the plunger |12 and this is done by engagement of the1pin|62with the cam` |02.f.atl the time the piston52 is in fully retracted vposition..`

When the piston .52 is .inrfully retracted -position. it can be started in a forward direction under manual control-and also can be returnedto fully retracted position in any part of its working cycle also under manual or other control. This isaecomplished by a manually yor .otherwise operated three-way valve. |18, diagrammatically shownrin Fig. y10,'-which admits pressure -iluid from axpipe .ISO-.communicating with the pressure pipe-`||8 alternately in to the pipes |82 and |84' which'admit pressure oil behind the spring-pressed pistons |86 and |88 operating in the cylinder |90. Said pistons are movable into engagement with a pin |92 carried by the valve slide |68 and are arranged to vmove said valve slide and-the arm`A |60 in oppositedirections. When the piston 5'2 -is inla retracted position. less than its fully retractedlpositiony but sufficiently to clear the drillfrom the work, in an intermediate part of its cycle of operations, the piston is adapted to be reversedand advanced by the operation of a pistonvalve |94 operating ina cylinder |96, see Figs. lA and-.10, carriedby a valve block |98.secured to the outer face of the valve carrying plate |54. ,Said .valve |94 is normally biased by Aa spring -200.,into a closed position but, when the valve stem 502 is depressed, the valve is adapted to admit pressure riunito new from the pipe 204 through. the pipe 266 and into the'pipe |84, thereby to move the piston |88 Vand cause `the reversal of the :valves |22, |24, the arm :|60 and the piston 5'2. Many of the actual piping connections of the parts illustrated in Fig. 10 have been omitted or modiedto aid in a vclearer understanding of the invention. For-instance, fluid'l passages` here shown as pipes, such for. instance, as vexhaustpipes |28, |30 are not actually as shown, the .exhaustports of the valves merely4 discharginginto ja space which. is above .the oil Vreservoir v| I2 that is.located inthe bottom ofthe frame 40.0f themechanism.-4

.1,- It willnow be understood that the piston 52 ca- 7 advance at a rapid -rate until the pin |62 .rides upon the dwell portion 80 of the cam .block 16, whereupon the piston advances at a yslower speed until the arm |60 is moved into a reversed position, whereupon the piston retracts rapidly. In accordance with this invention, the piston` 52 and the tool associated therewith, are required autovIn'atically to make .a plurality of high speed and low speed advancing movements into successively advanced positions and alternated with retractlin'gmovements to the same position and terminated with a retraoting movement to a fur-ther and fully retracted position. The nature of this workrequiring these operations is best illustrated inFi'gs. 23 through 28. initial position of the 'work b and the `drill a at the Lbeginning of a cycle. The drill azis required to advance ata fast rate .up to the lsurface of the work 'b land then `to advance at a slow rate into the work to some 'position shown inFig. 24 from which iposition the drill is retracted :rapidly into theposition as :illustrated in Fig. 25, where the drillris suiiciently clear of the work so 'that the chipscan fall away rfrom the vdrill and permit thef'drill point to be `bathed in the coolant that is `customarily ilowed upon the surface yof the work at 'the mouth of the Ahole whereby to .cool the drill point vand `prevent it from .overheating and-losing its cutting edge. The drill is then desired -toV be advanced rapidly to the .bottom of the hole into the position illustrated inFig. .26 and Vthen'further into the work at slow Vspeed into 'some .position as illustrated in Fig. 27. The drill is then required to be retracted into the position illustrated .in Fig. 26, if the hole is not yet deep enough, and then advanced again in ithe manner illustrated `in IFigs. 26 and 27, or if the .hole is deep enough. to be retractedinto the iinal fposition-illustrated in Fig. 28. These results areiaccomplished byholding the cam block 16 startionary when it is in slow speed engagement with thepin |62 of :thearm |60 so that V.the.-slide..6'4, which Vmoves withthe drill. can'move the required Adistance without-carrying the cam block with it. When this distance -is reached, thecamrblockis caused to move withthe slide -While a hydraulic control rmeans Yis provided ifor lmoving theycontrolling-arm |60 Vintofreverse position'so that the 4tool-and theslide and the cam block areretracted as 4a unit and .then advancedwith .thescam block Vina ldifferent position v.on the slide. 'To accomplish thisfthere is leading from the top of cylinder 54 apipef20| which communicates withan in1etpassage203 ina valve body 202. The` passage v203 communicates vwith the passage 204 i which, -v in turn, communicates withY an outlet passage 208. Between'thepassages 203 Vancl204, Aavvalve seat 205 isi provided .in .thexvalvebody .-12012 upon-Which is adaptedfto seatA avalve'or'metering pin-206. Themetering.pin`206'isfprovided with Fig. 23 represents :the

lazthreadedshank 201 :which-extendsfeXteriorly-of the .valve/body i202.. The head Yof :thezyalve :or metering; pin 20E-.is .provided with va `screw-driver vslotfor;adjusting'the'valve onV the rseat 3205 andzis heldin xed position byJa lock nut-25.0.l .Leading frorn'theipassage 20.8 lis a conduitllwhich come municates attheitop. of a. cylinder 2Ii0Lin which is vdisposed the piston `2| I. 'LeadingzfromL the cylinder 2I0 from .the` opposite .side ofthejpiston 2H is :a conduit `212 which 'communicates with 8 As previously described, the .tool or drill 29 .erleters the Work piece upon the ldownward movement of the piston 52 in the normal manner of 'a rapid approach to the work andslovv advancement in the work; As the luidor oil under vpressure enters the top of the cylinder 54 to advance the piston 52 and the tool downwardly, a portion will pass from .the cylinder .through conduit 2 I0, passages 204, 208, and conduit 209 into :the top of cylinder 210 moving the piston 2I| towards the opposite end ,in its cylinder.. The passage of `oil to the cylinder 2| 0 will -bethrottled by the setting of the .metering pin 206 which determines the time of travel for thepiston 2'II to'complete its stroke. The'stroke will determine the dept-h desired that the tool should .enter the work piece before its withdrawal. l On the downward tra-.vel of the piston v2| it -wi-ll rock the arm 2I3 which, through Ashaft |58, will rockarm .|64 carrying the pin |62 out of 4engagement with'the carnfbody 16 and simultaneously .through .the rocking of arm |64 engage valve |20 for reversing the flow of fluid to :the cylinder 54.- A reverse iiow of fluid .to the cylinder 54 will move the piston `52 and also the piston 2I| to the top -of'their `respective `Vcylinders. The lower ends of the cylinders are rjoined in communication ,by pipe 2|2. The fluid or oil above the piston '2 I I .will Vflow outwardly through pipe 209, passages 208 2and203, conduit 20|,Ainto the-cylinder above the vpiston-52, thence out through conduit |42 through already described circuit of valves and passageways to the reservoir I I2. A check valve is provided atthe junctionof passageway 208 and passageway 203 whichcomprises a ball 2I6 held by spring '2|1 upon seat 2I9 which vis formed at the `exit of passageway 208% :As the tool is retracted, the -slide barv 64 ,together with v.the cam block 16, which has been partially moved by pin |62 .towards the right on bar 64, lis carried .to the right, see Fig. 10,*until the piston 52reaches the V'top of its cylinder. ,As the .bar 64 reaches therend of its travel, latch lever |06 engages cam .j310si1fcientlyrocking the cam-to press theplunger 502 and through -the operation of valve lljhydraulically resetthemachine for'advancing 'the tool towards and into the work piece, aspreviously described. On each cycle .of operation, the cam block 1,6 ,is carried further along the bar'64 until it has-reachediits maximum point ofetravel which is determined'by the depthithat thetooljis to enter'theiworkypiece. At `this point, which isnthe last or riinal down stroke vof zthe .dri1l'29, arm 31 will jstrikethe' stop 98 rocking arm 31| until itstrikes abutment i312 i projecting from cam 'block 16, see Fig. 22. As

the arm `31| is vmountedto the viramexlw ofthe machine, theicam lblock-.16.willLbe held stationary as fthe bar :64 :travels to -thegright-which is a :ref traction of .the tool-from the-work, piece, thereby placingthe cam block 16 over tothe left endof the slide, see Fig. 10. .Asthecamblockreaohes theextreme left positionof the slide'pan extended finger :360..fwill .engage arm 31| vrocking,'itfinto neutral position, see.-Fig.5;1.4. The arm is grooved on its` under .face '.to permitithefahutment` 3.12 to passz-underneathwhen the arm is in neutralfposi-v tion .during the V.intermediate zcycling operation. Simultaneously. as. the` cam block 116 is moved to its extreme left position in the slide, the iinger 365 carriedbylblock 1.6 engages Land rocks latch lever I06.\to;prevent its engagement.withaoarn 3170. and' thereby Vv'preventing the tripping of E'the valve.'A I 96 yforresetting; theuhydra'ulic feed forthe down `v.-str'oke .Band'fthe ,maohineif is thus auto- 'matieallY-'Lsllopped f manual yresetting .l of.vv the valve |96 or by manually-resetting the reversing valve |18, aspreviously described, ,will start the machine upon the same cycling loperation upon the next or new work piece.' As the. engagementof thestop with the'latch lever |06 does not provide for a'uniform stopping of the machine, thereby making it dilcult, for close precision work, a' inal stop is provided which comprises a block 300 havingan ladjustable pin 30|. The block 300 is set upon the table of the machine or in alignment with the-work piece in a manner whereby the slide 36 may abut and come to rest against the'pin 30 I. The height ofthe block 300'withthe adjustment 30| will be made corresponding with'the depth desired! for the tool or drill 29 to enter into the work piece '23, thereby giving uniform depth to eachpiece that has to be drilled. y

It will be noted that there is thusprovi'ded'an adjustable timing mechanism for advancing and retracting thetool into the'wo'rk piece; The degree of advancement is dependent upon the iiow of the uid to'cylinder 2 0. Theoperator, by ad- J'ustment of the metering valve 206, vcan adjustably predetermine the timing of the advance and withdrawal cycles of the tool. Should the tool meet no variation in resistance, the cycles would be uniform but adjustable in timing as determined'by the restricted flow of iluid into the cylinder 54. But, frequently', thetool because Y'of variation in heat treating of work'pieces,` et'c., meetsa change in resistance which tends to build upa pressure for advancing thelpiston l52, therebyy causing an increase in `volume of the iluid llowing into the cylinder 2 0 and accelerating the advance of the piston 2|| .to the deceleration of the travel-of the piston 52. l,The faster travelling of -the piston 2|| will cause a'quicker withdrawal ofthe tooLthus permitting the tool to clearitselfof chips andrprovide for cooling sooner vthan the setting wasmadefor normal cycling operation,

and, therefore, operate in shorter steps the harder the work.. i l I.

Attention `is called'to patent-to IIirvonen, No. 2,073,518, upon which this inventionl isy based Yand toA which it is anaddition. All `of the Hirvonen mechanismis incorporated herein although not in 'all instances described at length. Particular reference is made however tothe overloadzreversal-mechanism of the-Hirvonen device, which mechanism is made a part .ofrthis-case because the overload device of Hirvonen is` necessary for protection exactly as before,I `but now combining- Awith the new timing ldevice to 'create the most eilicient and flexible tool of the class described ever presented.

`It.` occasionally happens that a chip lodges4 under'the cutting edge of the drill and rotates therewith and prevents the drill from cutting' and thereby advancing. In this levent, the back pressure onthe piston drops andv causes a greater piston-advancing pressureto be built up on thev other side of the piston. Hence the pressure on the drill becomes greater and the drill may break.

Mechanism is provided to prevent the application of too much pressure on the drill and, when the pressure exceeds va predetermined amount, to retract thedrill from the work so as tol clear the chip from under Ethe cutting edge-of the drill, and ythen to return the drill-into thework.l If the drill is unable to cut, due to the continued presence of the chip or for other reasons, the

drill is caused to be automatically retracted and advanced until the conditions causing the high pressure on the drill, or other tool, have dis-.-

10 appeared, whereupon the normal cycle of operation will be resumed. The arrangement is such thatthe retracting movement due to the high drill pressure does not advance the cycle of operation, that is,` the retraction of the drill does not cause the cam block to be shifted along its slide. tion of the tool from the work due to a high pressure on the tool includes a piston valve 284, see Figs. el and 10, located in a cylinder 286 of the plate |98 and urged by a spring 288 into a lowermost position Where it closes the high pressure port 290 and opens the reversing port 292. The high pressure port is connected by a pipe or duct 296 with the full pressure source. The port 292 is connected by a pipe 298 to admit high pressure behind the reversing piston |86 so as to effect the retraction of thetool. The space under the piston valve 284 is connected by a duct or pipe 400 with the pushing side of the piston 52 and is at all times subjected to the oil pressurel on the piston. Under normal working conditions, the spring 288 holds the pistonY valve 284 in itsv lowermost position, so that high pressure oil is isolated from the reversing piston |86. When, however, the oil pressure on the pushing side of the piston 52 becomes excessively high, as when a chip becomes lodged under the cutting edge of the drill, or when the drill'becomes dull, the pressure through the pipe 400 overcomes the spring pressure and raises the piston valve and thus establishes full oil pressure on the reversing piston |86, which then operates to reverse the valve mechanism of the piston 52 and eiect the retraction of the piston at high The piston and tool retract until thev speed. tool is clearl of thel work at which position the latch lever |06 -depresses the advancing valve' |94 and reverses the position of the aforesaidV valve mechanism and hence causes the tool to advanceas before, that is, rst rapidly downto the original point of engagement of the tool and the'A work and thence slowly. The tool will automatically retract and advance inv the aforesaid-` the lengths and-rates of the advance and hencev does not change the position'of the cam'block-'IS or its slide and so doesnot modify the usual 'work cycle. The pressure of the spring 288 on" the piston valve 284 and hence the oil pressure ati which the valve will be elevatedcan bev varied by screwing a sleeve 402, in which the upper end of the vspring 288 is seated, into or out of the plate |08, thus to vary the compression of the spring. Said sleeve canbe rotated by aring v404y which is axially loose thereon but has a spline and slot connection therewith. A lock nut 406 clamps the ring in any adjusted position of the sleeve.

chine drills in steps which will not Vary with changes in resistance dueto variation in hardness of work, although of course the device takes care of other unexpected changes in working conditions.l The, present invention, added tothe Hirvonen machine, provides for drilling vholes in steps that vary in length'with change in hardness of Work thus prolonging the life and permitting faster production.

The mechanism for effecting the retrac Now it will be clear that the-Hirvonen ma-` of the tool This Vcase is a continuation of Ser. ,-No. 562,212 .filed November 6, 1941i, now abandoned.

What I claim as new is:

`l. A machine of the class described, comprising: a movable tool holder movable toward 'and away from a work-piece; a cylinder; a piston slidably mounted in said cylinder and connected to said tool holder for, upon delivery of liquid under pressure to either side of said piston, moving said holder toward or away from a workpiece; a valve mechanism controlling delivery of liquid` to either side of said piston; a Vroclralole actuating member moving said valve mechanism from one position to another; a slide bar connected to and movable in lunison with said piston; cam surfaces carried by said slide bar and ',co-

operating with said actuating member .to 'controlv der and a second conduit connecting the other sides of the respective cylinders, increased pressure on one side of the rst named piston resulting from increased resistance of movement of the tool holder toward the work effecting an increase of fluid volume and hence acceleration of movement of said second-named piston in one direction; and a piston rod `connected to said second named piston and extending outwardly from said second named cylinder and engaging said rockable bar and effecting 'a rocking of the same in said direction upon movement of said second named piston in said direction.

2. A machine of Vthe class described, comprising: a movable tool holder movable toward and away from a work-piece; a cylinder; a piston slidably mounted in said cylinder and connected to said tool holder for, upon delivery of liquid under pressure to either side of said piston, moving said holder toward or away from a workpiece; a cylinder; a piston slidably mounted in i said ,cylinder and connected to said tool holderv for, upon delivery of liquid under pressure Vto either side of said piston, moving said holder toward or away from a work-piece; a valve mechanism controlling delivery of liquid to either side of said piston, a rockable actuating member moving said valve mechanism from one position to another; a slide bar connected to and movable in unison with said piston; cam surfaces carried by said slide bar andv cooperating with said actuating member to control the movement of said work tool toward and away from said workpiece and controlling the speed of movement at various positions yof movement; a rockable bar connected to said actuating member and, upon rocking in one direction, moving said valve mechanism to position shortening the time for a reverse movement of said piston for moving the tool holder away from the Work-piece; a second cylinder; a piston slidably mounted in said second cylinder; a conduit connecting one side of the second-named cylinder to the corresponding side of the rst-named cylinder and a second conduit connecting the other sides of the respective cylinders, increased pressure on one side oftherstnamedpiston resulting from increased resistance of movement ofthe tool holder toward the Lwork reflecting an increased'movement of said second named piston fin one direction; and :a piston rod-connected'to VVsaid second :named-,piston and extending outwardly from said second named cylinder and engaging saidV rockable :bar andeffecting a rocking of the same in said direction upon movement of said second vnamed vpiston in 4said direction; and a manually operable means controlling the now of liquid `frornzone side of said rst named cylinder .to yone side of said second named cylinder.

v3.y A machine of the class described, comprising: a movable tool `holder movable toward 'and away .from a Work-piece; a cylinder; a piston slidablymounted in said cylinder and connected to said tool holder for, upondelivery of'liduid under `pressure to either sideo'f said piston, moving said holder toward or Yaway .froma workpiece; a valve mechanism `controlling delivery of liquid to either side Aof said '.piston",v a .rockable actuating member moving said valvemechanism from yone position to another; a slide bar connected .to and movablev in unison `withY vsaid piston; cam surfaces carried'by saidslide .bar and cooperating with said actuating Amember to :control the movement of said work tool toward and away `from said work-piece 'and controlling the speed of movement at'various positions .oftmovement; a rockable barconnectedtoV said actuating member and, upon `rocking `one direction, moving said valve mechanism Ato positionsshortening the time for a reverse movement of said piston for `moving the tool holder away from the work-piece; a second cylinder; a piston slidably mounted in said second cylindena conduitconnectin'g one sidel of the second-named cylinder to the corresponding side of the .nist-named cylinder and `a secondl conduit connectingithe other .sides 'of .the respective cylinders,r increased pressure .on `one side of the iirst named piston resulting from increased resistance of movement of the tool holder toward the work effecting an increased movement of said second named piston in one direction; and a piston `rod connected to said second named piston and extending outwardly from said second named cylinder for engaging said rockable bar and eiecting a rocking of the same in said direction upon movement of said second 'named piston in said direction; and a manually operable means controlling the iiow of liquid `from one side of said .first .named cylinder to one side of said second named cylinder, said cam surfaces being movable into and out of engagement with said actuating member; and means reversing the direction of travel of the Vpiston in said first-named cylinder for effecting a movement of the tool holder toward the work-piece, upon disengagement of said cam surfaces vvith saidY actuating member upon withdrawal of said tool holder a predetermined distance.

4. A machine of the class described, comprising: a movable tool holder movable toward and away ,from a work-piece; a cylinder; a piston slidably Vmounted in said cylinder and connected to said tool holder for, upon delivery of liquid under pressure to either side of said piston, moving said holder toward or away from a work-v` piece; a valve mechanism controlling delivery of liquid to either side of said piston, an actuating member moving said valve mechanism from one position to another; a slide bar connected to and movable in unisonwith said piston; cam surl'13 faces` carried by' said' slide bar and vcooperating with said actuating member to control 'the movement'offsaid :worktool toward and away from said work-piece yandcontrolling the speed of movementat vario'us'positions of movement; av movable bar connected to said actuating member and, upon moving in one direction, moving said valve mechanism vto position shortening the y time for a reverse'movement of said piston moving the tool holder away from the work-piece; a second cylinder; av piston f slidablymoiint'ed in rsai'd second cylinder; aconduit connecting one side of the second-name'dcylinder to fthe corresponding side of the rst-named cylinder and a second conduit connecting the other sides of the respective cylinders, increased pressure on one side of the iirst named piston resulting from increased resistance of movement of the tool holder toward the work effecting an increased movement of said second named piston in one direction; and a piston rod connected to said second named piston and extending outwardly from said second named cylinder and engaging said movable bar and eifecting a movement of the same in said direction upon movement of said second named piston in said direction.

5. A machine of the class described, comprising: a movable tool holder movable toward and away from a work-piece; a cylinder; a piston slidably mounted in,v said cylinder and connected to said tool holder for, upon delivery of liquid under pressure to either side of said piston, moving said holder toward or away from a workpiece; a cylinder; a piston slidably mounted in said cylinder and connected to said Atool holder for, upon delivery of liquid under pressure to either side of said piston, moving said holder toward or away from a work-piece; a valve mechanism for controlling delivery of liquid to either side of said piston; an actuating member moving said valve mechanism from one position to yanother; a slide bar connected to and movable in unison with said piston; cam surfaces carried by said slide bar and cooperating with said actuating member to control the movement of said work tool toward and away from said work-piece and controlling the speed of movement vat various positions of movement; a movable bar connected to said actuating member and, upon moving in one direction, for moving said valve mechanism to position shortening the time for a reverse movement of said piston for moving the tool holder away from the work-piece; a second cylinder; a piston slidably mounted in said second cylinder; a conduit connecting one side of the second-named cylinder to the corresponding side of the first-named cylinder and a second conduit connecting the other sides of the respective cylinders, increased pressure on one side of d the first named piston resulting from increasedresistance of movement of the tool holder toward the work effecting a movement of said second named piston in one direction; and a piston rod connected to said second named piston and eX- tending outwardly from said second named cylinder and engaging said movable bar and effecting a motion of the same in said direction uponA movement of said second named piston in said direction; and a manually operable means for controlling the i'low of liquid from one side of said first named cylinder to one side of said secaway from a work-piece; a cylinder; a piston' slidably mounted in said'-cylinderandconnected to said tool'` holder for, upon': delivery `of-liquid under pressure to either'sideof said piston; moving said holderv toward'A or 'away lfromja workpiece; Va valve mechanism controlling delivery of liquid to either side of said piston;-'an actuating member-movingV said valve mechanismjfroinA one position to' another; a slide bar connected tov'and movable in unison withr said piston; cam surfaces carried by said slide bar andcoopeiating' with'l said actuating `member rto control the movement of said work tool toward and away from said work-piece and controlling thelspeed of! movement; at various positions of movement; a movable bar connected to said actuating member and, upon moving in one direction, moving said valve mechanism to position shortening the time for a reverse movement of said piston for moving the tool holder away from the workpiece; a second cylinder; a piston slidably mounted in said second cylinder; a conduit connecting one side of the second-named cylinder to the corresponding side of the first-named cylinder and a second conduit connecting the other sides of the respective cylinders, increased pressure on one side of the iirst named piston resulting from increased resistance of movement of the tool holder toward the work effecting a. movement of said second named piston in one direction; and a piston rod connected to said second named piston and extending outwardly from said second named cylinder engaging said movable bar and effecting a motion of the same in said direction upon movement of said second named piston in said direction; and a manually operable means reversing the direction of travel of the piston in said rst named cylinder for effecting a movement of the tool holder toward the work-piece controlling the ow of liquid from one side of said rst named cylinder to one side of said second named cylinder, said cam surfaces being movable into and out of engagement with said actuating member; and means for reversing upon disengagement of said cam surfaces with said actuating member upon withdrawal of said tool holder a predetermined distance.

7. Timing mechanism for a machine tool comprising a tool holder movable to and from a work piece, a main cylinder and piston therefor, a source of fluid pressure, a valve for controlling delivery of uid to either end of the cylinder, a valve actuating member to eiect reversal of the piston travel, and a uid operated device to operate the valve actuating member, said device comprising a second cylinder, a piston and piston rod therefor, and means moved by the piston rod and connected to the valve actuating member, said second cylinder being directly connected at its ends to corresponding ends of the main cylinder, said second piston being moved in the second cylinder in a direction to cause operation of the valve actuating member by reason of the flow of iiuid received from the side of the main piston occasioning the working stroke of the tool holder, said ow being dependent upon pressure in the cylinder and increasing at higher pressures and decreasing at lower pressures to automatically vary the timing of the tool stroke.

8. Tool stroke timing mechanism for a machine tool comprising a tool holder movable to and from a work piece, a main cylinder and piston therefor, a source of uid pressure, a valve for controlling delivery of fluid to either end of the cylinder, a valve actuating member to effect yiflwersel of vthe lpistonv travel, and a .uid' opermain cylinder to the working side of 'the second ,liked device to .operate the lveuve actuating mem cylinden: bcr-saiddevce comprising@V secondcyiinder, a n piston and piston rod therefor, andmeans'moved f Y n I n Y 'by the-piston rod `emdconnected to the valve REFERENCES CIT-ED actuating member; said second cylinder being The following references are of record in lthe directly connected at `its ends to corresponding me of this pafnt; c

ends` of the main cylinder, `seid second piston FRED W. KRIEWML beingmoved in the second cylinder in a' direction UNITED STATES PATENTS borauseoperation of the valve `actuating mem- 10 Number Name Date ber by reason of the volume of fluid received from 2,073,518 Hrvonen Mar. 9, 1937 the-*side of the main piston occasioning therwork- 2,079,640 Y Vickers et al May 11, 1937 ingstroke of the toolyholder, Vmeans to vadjust 2,178,915 MCKSQS al N0V- 7. 1939 thevfiow of uid fromihe Working side of-the 

